1. Field
Aspects of embodiments of the present invention relate to a rechargeable battery.
2. Description of the Related Art
Unlike a primary battery, a rechargeable battery is capable of being charged and discharged repeatedly. A small capacity rechargeable battery may be used for a small electronic device such as a mobile phone, a laptop computer, and a camcorder. A large capacity rechargeable battery may be used as a power source for driving a motor of a hybrid vehicle, for example.
Recently, a high power rechargeable battery using high energy density non-aqueous electrolyte has been developed. The high power rechargeable battery may be used for a device requiring high power, such as a driving motor of an electric vehicle.
The rechargeable battery includes an electrode assembly, a case housing the electrode assembly, a cap plate for closing and sealing an opening of the case, and an electrode terminal penetrating the cap plate and electrically connected to the electrode assembly. Here, the electrode assembly is formed by winding a positive electrode and a negative electrode with a separator interposed therebetween.
Since the rechargeable battery is charged and discharged repeatedly, heat may be excessively generated inside the case, and the electrolyte solution may decompose. Such heat generation or electrolyte solution decomposition may increase the internal pressure of the rechargeable battery. The increase of the internal pressure may cause ignition and explosion of the rechargeable battery. In order to prevent the ignition and the explosion caused by the increase of the internal pressure, an external short-circuit unit may be disposed at an outside of the case.
The external short-circuit unit shorts the positive electrode and the negative electrode of the electrode assembly from the outside of the rechargeable battery when the internal pressure of the rechargeable battery increases, thereby reducing a state of charge of the electrode assembly. However, the external short-circuit current may excessively penetrate the electrode assembly because the external short-circuit resistance value is small. Therefore, a safety problem may be caused in the electrode assembly.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.